#绝对值函数
import math

def my_abs(x):
      if x >=0:
            return x
      else:
            return -x

z=int(input('intput a int:'))
print(my_abs(z))
print ('sqrt :',math.sqrt(my_abs(z)))
#空函数 什么也不做
#pass
def my_pass(x):
      pass

if z is 5:
      pass

def move (n,a ,b ,c):
      if n==1:
            print(a,'-->',c)
      else:
            move(n-1,a,c,b)
            move(1,a,b,c)
            move(n-1,b,a,c)

move(3,'B','C','A')
print('-'*10)
move(3,'X','Y','Z')
print('-'*10)
move(2,'A','B','C')
